Ignition device



Nov. 3, 1942 w. E. KISHBAUGH IGNITION DEVICE Filed July 12, 1939INVENTOR m the appended claims. j In the drawing wherein like referencecharac- Patented Nov. 3, 1942 UNITED. STATES; PATENT OFFICE i 2,300, 30r IGNITION DEVICE Warren E. Kishbaugh, Sidney, N. Y., assignor to BendixAviation- Corporation, South Bend,-

Ind., a corporation of Delaware Application July 12,1939, Serial No.283,939

19 Claims.

This invention relates to ignition apparatus for use in-internalcombustion engines and more particularly to spark plugs and methods formaking the same. It has been heretofore proposed to provide annularground electrodes in spark plug bodies or shell and engage or securethem to the latter entirely around the inner periphery thereof by meansof soldering, welding or the like. Although this manner of securing theelectrodes in place has been quite satisfactory, difficulty has beenexperienced by way of having the same become loose and even drop outof'the plug during use. Those which drop out into the engine cylinderoften cause considerable damage to the cylinder and are apt to disablethe engine. If an' electrode becomes loose in its shell the conductionof heat therefrom to the shell" of the,

plug and, hence, to the surrounding atmosphere is materially reduced,thereby permitting the electrode to become overheated to a point whichmay cause precombustion in the cylinder. Inso-.

far as applicant is aware, no way has been ascertained for definitelydetermining whether or not an electrode has been soldered in place in a.sufficiently secure manner to insure its remaining tightly in placeduring operation of an engine. It is not possible in each instance todetermine whether or not the solder has flowed properly, for example,and whether or not it has become properly fused to the surfaces of thespark plug shell and the electrode.

Accordingly, one of the objects of the present invention is to provide aspark plug wherein the ground electrode is attached in the body or shellin a novel manner.

' with parts broken away, of a second form of ters refer to like partsthroughout the several views:

Fig. 2 is a bottom end view of the spark plug of Fig. 1";

Fig. 3 is a side elevation, partly in-section and spark plug embodyingthe invention; and

Fig. 4 is a bottom end view of the sparkplug illustrated in Fig. 3.

The forms of the invention shown in the drawing, by way of example, areillustrated as being embodied in radio shielded spark plugs, but it willbe understood, of course, that the invention is applicable to any othertype of spark plug whether shielded or unshieldede In Fig. 1 the sparkplug shown comprises a shell or body l0 which is adapted to bethreadedly secured in an engine cylinder (not shown) in a mannerwell-knownin the art and adapted to support a center electrode assemblycomprising an electrode withan enlarged head portion II and a spindlel2, the latter of which is surrounded in the conventional manner by atightly Another object of the invention is to provide novel means forsecuring annular ground electrodes in a spark plug body whereby it issub stantially impossible for the electrode 'to drop out of the shellinto the engine cylinder.

fitted copper sleeve l3. A mica sleeve or cigarette ll surrounds sleevel3 and tightly engages the walls of a bore through anut l5 thatthreadedly engages shell Ill. The upper ends of electrode spindle I 2and sleeves l3 and I4 project into a metallic shieldingbarrel l6 formedintegrally with or otherwise secured to gland nut l5 and is adapted tobe electrically connected to a source of high tension electrical currentin-a manner well understood in the art. Interposed between the-lower endof gland nut l5 and head portion ll of the electrode is a stack of micawashers I] A further object is to provide a novel method for securingground electrodes in spark plugs for use in'intemal combustion engines.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the .sameis read in connection with the accompanying drawing. It is .to beexpressly understood, howeve that the drawing is for the purpose ofillustration only and is not intended as a definition of the limits ofthe invention, reference being primarily had for this latter purpose toy Gil or other suitable insulating material.

Mounted in shell I in a-novel manner for electrical cooperation withelectrode II, I! is a ground electrode 08. In the form shown in Fig. 1said ground electrode is cup-like in general outline with cylindricalwall l9 thereof slidably fitting into an enlarged bore 20 at the lowerend of shell, l0 and butting against an internal shoulder M in thelatter that serves as a stop. For a purpose to hereinafter appear, theouter diameter of wall I9 ,is' slightly less than the diameter of bore20 and the internal'diameter of said wall is substantially equal to thenormal bore of shell Ill. Projecting radially. inward at a slightlydownward angle from wall 19 are a plurality of prongs 22 which cooperatewith-elec-' trode head H to form a spark gap.

The novel means for securing ground electrode l8, IS in shell lcomprises an annular groove 23 in the outer periphery of wall l9, saidgroove portions thereof are bent downwardly to form prongs 34, the innersurfaces of which extend substantially parallel .to the cone-shapedsurfaces of electrode head 21. For the purpose of mechanically holdingelectrode 32 in shell 3|, spaced portions 35 of the latter are pressedinwardly into overlapping engagement with the electrode, 1. fe., saidportions are preferably staked solder or other suitable binding mediummay be interposed between wall l9 and the inner wall of bore 20.Electrode I8 is thus doubly secured against removal or loosening. I

In assembling shell l0 and ground electrode l8, the former is firstcounter-bored to form the enlarged bore and shoulder 2|. The shell isthen washed with a suitable solvent to remove alldirt particles and thewalls of bore 20 are coated with a suitable soldering flux, such asborax, which may be in the form of a paste. The grooved electrode i8,which-is preferably not provided at this stage with slots 25, is thenplaced in the shell and the assembled parts are subjected intooverlapping relation with the outer face of electrode 32 in the samemanner that-tongues 24 are staked against the inner shoulder of groove23 in the embodiment of Fig.1. Thereafter the electrode may be solderedto shell 3| in accordance'with the novel method above-described inconnection with the first embodiment. The solder is'thus permitted toflow freely by gravity between. the periphery of electrode 32 and thesurface of bore 33 at the spaces between circumferentially spacedportions 'which are pressed into engagement with the outer surface ofthe electrode. In the process of assembling and securing the parts inthe manner illustrated in Figs. 3 and 4, the flux and solder arepreferably to a punching or staking operation in a die press I equippedwith tools for forming the tongues 24 that project into groove 23 andconstitute the mechanical holding means. Inproducing .the embodiment ofFigs. 1 and 2 a reciprocating punch with four equally spaced chisel-likeprongs is employed.

Shell [0 isnext supported by any suitable means in an invertedpositionand a ring of silver solder or other similar fusible material ispositioned around the projecting portion of electrode l8. Additionalflux adapted to promote the fusing of metalsmay now be placed on. thesolder ring and the entire assembly heated, preferably to a red heat, byany suitable means, such as an electrically heating coil surrounding theshell.

The solder ring is thus melted and flows readilyby gravity into groove23 and the clearance space between adjacent surfaces of wall l9 andenlarged bore 20. The flux previously placed on these surfacesfacilitates the fiow of the molten solder and insures the fusing thereofwith said surfaces. After the soldering operation, the shell andelectrodeassembly is pickled in acid to remove the scale therefrom andthereafter machined for the purpose of removing rough surfaces. Grooves25 are then milled in electrode I8 to form prongs 22 and the entireassembly is polished for assembly with the center electrode assemblyabove described. v

applied in accordance with the-novel method hereinabove described. i

There is thusprovided a spark plug wherein the ground electrode issecured in position in a novel manner to prevent loosening or lossthereof and to insure good heat conduction atall times between theelectrode and the spark plug shell.

A novel method is also provided for securingthe ground electrode in aspark plug'shell whereby said electrode is held in position bothmechanically and by metallic fusion. Additionally, the inventionprovides a novel method for manufacturing reliable spark plugs in aninexpensive manner. provided wherein heat conduction from the head ofthe center electrode is facilitated.

. Although only two embodiments of the inven tionhave been illustratedand described in de- -tail.it is to be expressly understood that thesame is not limited thereto. For example, various changes may be made inthe design and arrangement of parts illustrated without departing fromthe spirit and scope of the invention as will now be apparent to thoseskilled in the art. 'For a definition of the limits. of the invention,refer-- ence, is had primarily to the appended claims.

Whatisclaimedisr r t 1. A spark plug comprising an electrode as? semblyincluding a center electrode insulated from ground, a tubular shell forsupporting said assembly in an engine cylinder, one end of said shellhaving an enlarged bore, a ground electrode V mounted in said bore forforming a spark gap In the embodiment illustrated in Figs. 3 and 4,

a modified center electrode 26 having a tapered or cone-shaped headportion 27 is shown. A copper tube 28 is combined with said electrode ina novel manner to facilitate heat flow from the electrode head, theupper-surface of the latter being provided with an annular groove 29into which a flanged portion 30 of the copper tube extends. The surfaceengagement between head 21 and tube 28, which has high heatconductivity,

is thus materially increased, thereby increasing the rapidity of heattransfer from the electrode headto the tube.

Novelly secured in the lower end of shell 3| (Fig. 3) is a groundelectrode 32 having a .circular periphery engaging the walls of anenlarged bore 83 in the shell. The central portion of electrode 32 iscut away, as best seen in Fig. 4, and

with said center electrode. spaced portions of said shell being stakedinwardly into overlapping relation with portions of said groundelectrode, and solder interposed between and fused to the adjacentsurfaces of said-shell and said ground electrode.

2. In a spark plug, the combination of a tubular shell having anenlarged bore at one end thereof, an electrode having a portion with acircular periphery positioned in said bore, only circumferentiallyspaced portions .of-said shell at said end extending inwardly intooverlapping relatlon with partsof said electrode, and means interposedbetween and fused to the adjacent surfaces 'of said electrode fiid saidshell.

3. In a spark plug, the combination of a tubular shell having anenlargedbore at one end thereof, n electrode having a portion with a circularper phery positioned in said bore, said .por-

A novelly constructed spark plug is also aaoonso tion having an annulargroove therein, circumferentially spaced portions of said shellextending into said groove, and means interposed between and fused tothe adjacent surfaces of said electrode and shell, said last-named meansfilling said groove.

4. In a spark plug, the combination of a tubular shell having anenlarged bore at one end thereof forming an internal shoulder therein,an electrode engaging said shoulder and having a periphery conforming tosaid bore, only circum ferentially spaced portions of said shellextending inwardly in a radial direction and'engaging said electrode forholding the latter in positionin said shell, and means interposedbetween and fused to adjacent surfaces of said electrode and shell.

5. In a spark plug, the combination of a tubular shell having anenlarged bore at one end thereof, an electrode having a peripheryconforming to said bore and positioned therein, said electrode having anannular groove in the Peripheral surface thereof, said groove having theouter edge thereof substantially flush with the .end of said shell,circumferentially spacedportions of said shell extending into saidgroove and engaging said electrode, and fusible'means substantiallyfilling said groove and the clearance space between said shell andelectrode for joining the same together. a

6. Ina spark plug, the combination of a tuhular shell having an enlargedbore at one end thereof, an electrode having a portion with a andcircumferentially spaced portions of said shell extending into saidgroove and engaging said electrode for holding the latter in said shell.

7. In a spark plug, the combination of a tubular shell having anenlarged bore at oneend so thereof, an electrode having a circularperiphery positioned in said core, and circumferentially spaced portionsof said shell staked inwardly to engage the outer surface of saidelectrode for holding the latter in the shell.

8. The method of making spark plugs whic includes the steps of making atubular shell having an enlarged bore at one end thereof, coating thewall of said bore with a soldering flux, positioning an electrode havinga circular periphery with a circumferential groove in said bore, sub-.jecting said shell to a punching operation to press fusible material.

9: The method of manufacturingspark plugs which comprises the steps ofmaking a tubular shell having an enlarged bore at one end thereof,coating the wall of said bore with a flux adapted to promote the fusionof metals, positioning anelectrode having a circular periphery in saidbore, subjecting said shell to a punching operation to presscircumferentially spaced portions thereof inwardly into overlappingengagement with portions of said electrode, and causing a molten fusiblematerial to fiow into the clearance space between the adjacent surfacesof said shell and electrode.

10. The method of mamng spark plugs which 75 ing the wall of said borewith a flux adapted topromote fusion of metals, positioning an electrodehaving a circular periphery and a circumferential peripheral groove insaid bore, subjecting said shell to a punching operation to presscircumferentially spaced portions thereof into said groove, and causinga'molten fusible material to flow into said groove and into theclearance space between the adjacent surfaces of said shell andelectrode.

-1l. The method of manufacturing spark plugs which includes making atubular shell having an enlarged bore at one end thereof, positioning anelectrode having a circular periphery in said bore, andsubjecting saidshell to a punching operation for simultaneously "pressingcircumferentially spaced portions thereof into overlapping relation withportions of said electrode.

12. The method of manufacturing spark plugs which includes making atubular. shell having an enlarged bore at one endthereof, placing anelectrode having a circular periphery and circumferential groove thereinin said bore, and subjecting said shell to a'punching operation tosimultaneously press circumferentially spaced portions thereof into saidgroove.

' 13. In a spark plug, an electrode assembly comprising a centerelectrode having a head portion and a stem portion, said head portionhaving an annular groove in the face thereof-adjacent said stem portion,the inner periphery of said groove constituting a continuation of saidstem portion,

and a metallic tube having high heat conductivity surrounding said stemand having a flanged portion substantially filling said groove.

14. In a spark plug comprising an electrode assembly including a centerelectrode having a 'head portion and a-stem portion, said head portionhaving an annular groove in the face thereof adjacent said stem, theinner periphery of said groove constituting a continuation of said stem,a metallic tube having high heat conductivity surrounding said stem andhaving a flanged portion substantially filling said groove, a tubularshell for supporting said 1 assembly in an engine cylinder, one end ofsaid shell having an enlarged bore, a ground electrode mounted insaid'bore for forming a spark gap with the head portion of said centerelectrode, spaced portions of said shell being pressed inwardly intooverlapping relation with portions of said ground electrode, and fusiblemeans interposed between and fused to the adjacent surfaces of saidground electrode and said shell.

15. In a spark plug, the combination of a tub.11 lar' shell having abore therein, an electrode having a portion with a circular peripherypositioned in said bore at one end thereof, said portion having acircumferentially extending groove therein, and a portion of said shellat the end thereof staked into said groove and engaging said electrodefor holding the latter in the shell.

16. In a spark plug, the combination of a tubular shell having anenlarged bore, at one end thereof forming an internal shoulder therein,an electrode engaging said shoulder and having aperiphery conforming *tosaid bore, and at least one portion of said shell being staked inwardlyinto overlapping relation with said electrode for holding the latterinposition in said shell, the circumferential extent of said portion beingless than the circumference of the shell.

tion withsaid electrode.

18. In a spark plug, the combination of a tubular shell having anenlarged bore at one end thereof, an electrode having a. portion with acircular periphery positioned in said bore, said portion havingacircumiferentially extending recess therein, and means interposedbetween and fused to adjacent surfaces of electrode and shell, saidmeans extending into said recess.

1 19. The method of manufacturing a spark plug which includes making atubular shell having an enlarged bore at one end thereof, positioning anelectrode having a circular periphery in said bore,

and staking the end'cf said shell by pressing a wedge-like tool intosaid end intermediate the inner and outer peripheries of the shell topress at least a portion thereof of less circumferential extent than thecircumference of said shell into overlapping relation with saidelectrode to mechanically lock the latter in said shell.

WARREN E. KISHBAUGH.

